GS-16 Stratigraphic correlation of multiple bentonite horizons from the Upper Cretaceous Pierre Shale (Pembina Member) of Manitoba (part of NTS 62G1, 2) by J. Hatcher1 and J.D. Bamburak Hatcher, J. and Bamburak, J.D. 2010: Stratigraphic correlation of multiple bentonite horizons from the Upper Creta- ceous Pierre Shale (Pembina Member) of Manitoba (part of NTS 62G1, 2); in Report of Activities 2010, Manitoba Innovation, Energy and Mines, Manitoba Geological Survey, p. 178–185. Summary Although previous attempts The Pembina Member of the Pierre Shale (Campa- have been made to correlate the nian, Cretaceous) consists of black carbonaceous shale Pembina Member bentonite in interspersed with numerous bentonite stringers (or seams), Manitoba with the Sharon Springs Formation (formally, deposited as volcanic ash, within the Western Interior Sea- the Sharon Springs Member of the Pierre Shale) in South way. The correlation of the bentonite seams is difficult, if Dakota and Wyoming, and with the Claggett Shale in not impossible, when it is based solely on visual observa- Montana, researchers have experienced limited success in tions, due to thickness variations and lack of lateral con- the correlation of this distinctive unit across the vastness tinuity. The purpose of this study, by the Canadian Fossil of the Western Interior. Furthermore, Quaternary uplift Discovery Centre in Morden, Manitoba, is to use fossil and glaciation, along with previous bentonite mining pollen and spores to correlate the bentonite horizons over activities, have often disturbed the bentonite seams from long geographic distance within the Pembina Member of a position of original horizontality, making it difficult to the Pierre Shale along the Manitoba Escarpment. This determine which bentonite horizons can be correlated data will be used as a control to study vertebrate fossils with fossil vertebrate localities at numerous sites along within their respective stratigraphic horizons; and could the Manitoba Escarpment. Based on previous benton- also be used to locate the thickest bentonite seam with the ite correlation studies reported by McNeil and Caldwell highest economic value within a 5 m thick assemblage of (1981), a similar method of palynological correlation has interbedded black shale and bentonite. been employed by the Canadian Fossil Discovery Centre (CFDC) within the Morden–Miami area of the Manitoba Escarpment. Introduction The Pembina Member of the Pierre Shale (Bam- burak and Nicolas, Figure GS-15-1, this volume) consists Pembina Member stratigraphy of black carbonaceous shale interbedded with numerous MacLean (1915) gave the name Pembina beds to bentonite stringers (or seams) deposited in the Western the lower thin, greyish black, noncalcareous carbona- Interior Seaway (Nicholls and Isaak, 1987; Cuthbertson ceous marine shale with numerous thin buff (to pinkish, et al., 2007; Konishi and Caldwell, 2009). Sedimentary creamy or off-white) bentonite seams that is overlain by rocks are exposed along the Manitoba Escarpment (Fig- an upper brownish shale, which usually forms the base of ure GS-16-1) with numerous Pembina Member outcrop the Pierre Shale in the Pembina Hills area (Figure GS-16- sites (adjacent to former quarries) located in the Mor- 3). McLearn and Wickenden (1936) raised the Pembina den–Miami area of southwestern Manitoba (Figure GS- beds to formation status as the Pembina Formation, but 16-2), and extending to the southeast into North Dakota. Wickenden (1945) reduced its status to a member of his Early attempts at regional correlation of the bentonite newly proposed Vermilion River Formation. McNeil and seams along the Manitoba Escarpment have indicated that Caldwell (1981) discarded Wickenden’s (1945) terminol- the lower Pembina Member seams lie within the Bacu- ogy and placed the Pembina Member stratigraphically lites obtusus Zone of the early Campanian (Nicholls and above the then recently recognized Gammon Ferruginous Isaak, 1987; Larson et al., 1997); however, no ammonites Member of Bannatyne (1970; Figure GS-16-3). How- have been discovered to date from the Pembina Member. ever, McNeil and Caldwell (1981) also indicated that if Consequently, McNeil and Caldwell (1981) assigned the the Gammon Ferruginous Member is absent, due to non- Pembina Member to the early late Campanian, as shown deposition or to postdepositional erosion during the Cre- in Figure GS-16-3, based on foraminifers considered to taceous, then the Pembina Member of the Pierre Shale be diagnostic of the Trochammina ribstonensis Zone. To can be seen to disconformably overlie the Boyne Mem- date, this has been the extent of palynological correlation ber of the Carlile Formation. The lower unit of the Pem- of bentonite seams in the Pembina Member of the Pierre bina Member passes gradationally upwards, with notably Shale in southwestern Manitoba. less intervening bentonite seams, into an upper unit of 1 Canadian Fossil Discovery Centre, 111-B Gilmour Street, Morden, Manitoba R6M 1N8 178 Manitoba Geological Survey Report of Activities 2010 Report of A A’ Turtle Mountain PERIOD/ ERA EPOCH Manitoba Pleistocene Escarpment shale, Paleocene Turtle lignite Mt. Fm. Winnipeg Boissevain CENOZOIC sandstone Assiniboine Red River Fm. River shale River Pierre Shale shale, bentonite Overburden shale, limestone shale Carlile Fm. sandstone, shaleshale, sandstone Cretaceous Favel Fm. Ashville Fm. limestone, shale Swan River Fm. evaporite, gypsum, red shale, sandstone MESOZOIC Melita Fm. limestone, dolomite, shale dolomite, shale Jurassic dolomite Reston Fm. evaporite, dolomite, shale, sandstone Amaranth Fm. Triassic limestone, dolomite Madisonlimestone Group sandstone, shale 300 Mississippian Souris River Fm. 52° Dawson Bay Fm. 200 Devonian Elk Point Group metres 100 Interlake Group Silurian ALEOZOIC PRECAMBRIAN 0 P Stonewall & Stony Mountain fms. 0 10 20 30 40 Assiniboine A’ kilometres R. Red River Fm. Winnipeg River innipeg Fm. Ordovician W A Red 49° 101° 0 100 96° 179 kilometres Figure GS-16-1: Cross-section of Paleozoic to Cenozoic formations in southern Manitoba (after Bamburak and Nicolas, 2009b, Figure GS-19-1). R9W1 R8W1 R7W1 R6W1 R5W1 R4W1 530000 540000 550000 560000 570000 Stephenfiel d ST13 Provincial C.N.R. Park ! Roseisle ! Graysville 245 245 ! ST ! ! Cardinal ST Stephenfield T6 0 ! 0 0 0 Le arys 0 0 0 8 ! 0 4 Babcock 8 5 4 !St. Lupicin 5 ! Five Corners ! ST338 Graham ST240 !Pomeroy T5 ! Deerwood 0 0 0 0 0 0 0 7 23 ST 0 4 7 5 Miami ! Rosebank 4 ! 5 Roland ST240 Ì ST244 Ì Ì 428 Site 15 ST ÌÌ T4 Site 30 Ì 0 Ì Mount Nebo 0 0 0 Ì 0 0 0 6 0 4 6 5 4 5 ÌÌ Manitou Ì ! Ì Ì T3 C. N.R. ÌÌ 0 0 0 0 0 0 Th ! ornhill 0 5 0 4 Morden 5 5 3 ! ST14 4 ST 32 5 ST434 ST Winkler! 0 0 0 ST432 0 3 5 ST528 T2 Chortitz Ì ! ! !Kaleida Site 9 Schanzenfeld 0 0 ! 0 0 Ì 0 0 Glencross 0 4 0 4 4 5 4 5 0 5 10 Ì Osterwick km ! Hochfeld ! ST31 Friedensfeld West Ì Approximate location of Ì ! form ! er quarries Brow Blumenfeld T1 ! n Site 9 Sample site 0 201 0 ST 0 0 0 0 Pembina Valley 0 3 ! Haskett 0 4 201 3 5 ST Provincial Park 4 Mowbray Windygates 5 ! ! Canada United States 540000 550000 560000 570000 Figure GS-16-2: Pembina Member outcrop sample and former quarry sites in the Morden–Miami area of southwestern Manitoba. Note: quarry locations are approximate and symbol may cover one or more sites. chocolate brown, waxy, less organic shale, and finally is similar to the Millwood Member in its composition and into the brownish green, waxy, noncarbonaceous shale of test results. the Millwood Member of the Pierre Shale. According to The lower Pembina Member can usually be seen Bannatyne (1970), the upper part of the Pembina Member in roadcuts and in ravines adjacent to almost 20 former in the Miami area exhibits some swelling properties, and mining operations (Figure GS-16-2) along the Manitoba 180 Manitoba Geological Survey Kirk (1930) McLearn & Wickenden PERIOD Tyrrell (1892) MacLean (1915) Wickenden (1945) & STAGE Pembina and Riding (1936) ERA Manitoba Escarpment Pembina Mountain Manitoba Escarpment Mountains Hudson Bay, Saskatchewan Boissevain Formation Maastrichtian Odanah Odanah beds Odanah beds Odanah “phase” series Riding Mountain Formation Formation Millwood beds Riding Mtn. beds Riding Mtn. unnamed member Millwood Campanian Pierre Formation series Pierre Formation Pembina beds Pierre Formation Pembina beds Pembina Formation Pembina Member Vermilion River beds Santonian Coniacian Cheval beds Boyne beds Boyne Member Boyne beds Boyne-Morden Late ACEOUS Formation ermilion River Formation Niobrara Morden beds Morden beds V Morden Member CRET Formation uronian Assiniboine limestone T Assiniboine beds Assiniboine Member Assiniboine beds Keld-Assiniboine Favel Niobrara Formation Formation Keld beds Keld beds Formation Keld Member upper Cenomanian shale member Benton Benton Ashville Ashville silt or sand Formation Shale beds Formation member or Benton Shale Ashville Formation lower shale member Early Albian Dakota Dakota Basal Swan River Swan River Formation Sandstone beds Formation Formation Jurassic PERIOD Nicolas (2009) & STAGE Tovell (1948) Bannatyne (1970) McNeil & Caldwell (1981) ERA Pembina Mountain Southwest Manitoba Manitoba Escarpment Southwest Manitoba outcrop belt Boissevain Formation Boissevain Formation Boissevain Formation Maastrichtian soft unnamed member Coulter Member Odanah beds Odanah Member hard Odanah Member Odanah Member Formation Formation Riding Mtn. Millwood beds Riding Mtn. Millwood Member Millwood Member Millwood Member Pembina Member Pierre Shale Pembina Member Pembina Member